The present invention relates to a semiconductor device. This semiconductor device can be suitably used, for example, as intelligent power device (IPD).
There are known intelligent power devices (IPDs) for automobile electrical system. An IPD includes current limit and current interrupt functions for protecting the device or harness when an abnormality, such as a load short-circuit, occurs. As used herein, the current limit function refers to a function of limiting the magnitude of the output current. The current interrupt function refers to a function of interrupting an excessive output current (overcurrent).
For example, Japanese Unexamined Patent Application Publication No. 2001-160747 discloses a semiconductor switching device having current limit and current interrupt functions. This semiconductor switching device includes a semiconductor switching element, overcurrent detection means, and load current control means. The semiconductor switching element provides or interrupts the power supply to the load. The overcurrent detection means detects an overcurrent by comparing a detected load current value with a first overcurrent reference value for determining an overcurrent state or with a second overcurrent reference value which is greater than the first overcurrent reference value and which is intended to determine a large overcurrent. The load current control means performs overcurrent interrupt control, that is, turns off the semiconductor switching element when the detected current value is greater than the second overcurrent reference value, that is, indicates a large overcurrent. The load current limit means also performs current limit control, that is, alternately turns on and off the semiconductor switching element to limit the load current when the detected current value is greater than the first overcurrent reference value and smaller than the second overcurrent reference value, that is, indicates a medium current.
A related-art example is a power supply switch circuit disclosed in Japanese Unexamined Patent Application Publication No. 2009-212704. This power supply switch circuit includes an output transistor, an output control unit, a sense transistor, an output current detection terminal, and a short-circuit detection unit. The output transistor is coupled between a power source terminal and an output terminal. The output control unit controls the conduction state of the output transistor in accordance with an input signal. The gate of the sense transistor is coupled to the gate of the output transistor so that the sense transistor detects an output current flowing into the output transistor. The output current detection terminal generates a detection voltage corresponding to the output current detected by the sense transistor. The short-circuit detection unit detects the short-circuit state of the output current detection terminal on the basis of the detection voltage and outputs a short-circuit control signal for stopping the output transistor or limiting the output current.
Japanese Unexamined Patent Application Publication No. 2001-345688 discloses a semiconductor switching element drive circuit. This semiconductor switching element drive circuit includes a semiconductor switching element 4, an overcurrent protection circuit 20, and a current limit circuit 10. The semiconductor switching element 4 includes a gate terminal 4a, a first terminal 4b, and a second terminal 4c, and applies a voltage to the gate terminal to pass the principal current between the first and second terminals. When the principal current is an overcurrent which has exceeded a predetermined current value i2 for a predetermined period of time or more, the overcurrent protection circuit 20 first reduces the principal current on a first slope and then reduces the principal current on a second slope, which is steeper than the first slope. When the principal current becomes a larger current than the overcurrent within a shorter period of time than the predetermined period of time, the current limit circuit 10 instantly reduces the voltage of the gate terminal.
Japanese Unexamined Patent Application Publication No. 2003-111264 discloses a power supply device having an overcurrent protection function, a load drive device, and power supply device for vehicle. This power supply device includes a semiconductor element 10, current detection means 13, and current limit means 14. The semiconductor element sends a current to the power receiving side via a wire. The current detection means 13 detects the current passing through the wire. When the current detected by the current detection means exceeds a current limit threshold, the current limit means 14 controls the semiconductor element to limit the current passing through the wire to the current limit threshold or less. The current limit threshold is set to the current value or less in accordance with wire burn-out characteristics, which indicate time-varying characteristics of the current value with which the wire burns out due to the current passing through the wire.
Japanese Unexamined Patent Application Publication Nos. 2009-171551 (US2009160498(A1)) and 2011-139404 (US2011163794(A1)) disclose circuits for discharging the gate charge of an output transistor.